USB: usbtmc: correct termination condition for reads.

Follow T&M convention of obeying EOM flag.  Avoid exception cases where
instrument response size matches a buffer size.

Signed-off-by: Steve Holland <sdh4@iastate.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/usb/class/usbtmc.c b/drivers/usb/class/usbtmc.c
index 91d3a94eeaa0..6395f22a58e1 100644
--- a/drivers/usb/class/usbtmc.c
+++ b/drivers/usb/class/usbtmc.c
@@ -485,7 +485,8 @@ static ssize_t usbtmc_read(struct file *filp, char __user *buf,
                 }
 
                 done += n_characters;
-                if (n_characters < USBTMC_SIZE_IOBUFFER)
+                /* Terminate if end-of-message bit recieved from device */
+                if ((buffer[8] &  0x01) && (actual >= n_characters + 12))
                         remaining = 0;
                 else
                         remaining -= n_characters;